It is known that silicone oils can be used for refrigerating mixtures providing oils having a viscosity in the range from 5 to 20 mm.sup.2 /s, as measured at 20.degree. C., are used (W. Simmler, "G-I-T Fachzeitschrift fur das Laboratorium," 6, 101, 189, 278 -1962-). Since the application in question is static by nature, it is immaterial if the viscosity is relatively high at low temperatures.
On the one hand, the refrigerants of the refrigerating machine circuit itself (halocarbon and halogenated hydrocarbon compounds, such as for example R.sup.11, R.sup.12, R.sup.22 and R.sup.502) have hitherto been used as low-viscosity refrigerants at low temperatures; on the other hand, aqueous solutions of alcohols (methanol, ethylene and propylene glycol) and of salts (calcium chloride, soda, etc.) are used, depending on the temperature range. The disadvantages of these refrigerants are well known. On account of their low flashpoint, lower alcohols require elaborate safety precautions and, in some cases, are toxic. Aqueous salt solutions are highly corrosive and have an excessive viscosity at low temperatures. Finally, the halocarbon and halogenated hydrocarbon compounds are partly responsible for the photochemical degradation of the ozone layer and, in some cases, are also toxic. Accordingly, mixtures of silicone oils with halocarbon and halogenated hydrocarbon compounds, as described for example in Japanese patent application 50/453500, are poor compromises.